Add optional padding data at the end to the bit source (is that the right place?...

[fjl] / dehuff.c

diff --git a/dehuff.c b/dehuff.c
index 3e0fd6c4ec86ab441ca36c921cb134d1cf842228..c4a65eea8a0619153bb9910cd5421db53bd01193 100644 (file)
--- a/dehuff.c
+++ b/dehuff.c
@@ -2,41 +2,13 @@
 #include <stdlib.h>
 #include <assert.h>
 
+#include "bytesource.h"
 #include "dehuff.h"
+#include "input.h"
 
-void reliable_read(raw_input_func_t* input_func, void* userdata, uint8_t* buf, size_t len)
+void read_huffman_tables(huffman_tables_t* dst, input_func_t* input_func, void* userdata)
 {
-       while (len > 0) {
-               ssize_t bytes_read = input_func(userdata, buf, len);
-               assert(bytes_read <= len);
-
-               // TODO: We need better error handling here. setjmp()/longjmp()
-               // should hopefully do the trick, but we need to take care for
-               // suspension.
-               if (bytes_read == (ssize_t)-1) {
-                       fprintf(stderr, "Input function returned error\n");
-                       exit(1);
-               }
-               if (bytes_read == 0) {
-                       fprintf(stderr, "Premature EOF\n");
-                       exit(1);
-               }
-
-               buf += bytes_read;
-               len -= bytes_read;
-       }
-}
-
-uint16_t read_length(raw_input_func_t* input_func, void* userdata)
-{
-       uint8_t buf[2];
-       reliable_read(input_func, userdata, buf, 2);
-       return (buf[0] << 8) | buf[1];
-}
-
-void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, void* userdata)
-{
-       size_t len = read_length(input_func, userdata);
+       size_t len = read_uint16(input_func, userdata);
        assert(len > 2);
        len -= 2;
 
@@ -60,7 +32,7 @@ void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, vo
                        exit(1);
                }
 
-               struct huffman_table* tbl = dst[table_class][table_dest];
+               struct huffman_table* tbl = &((*dst)[table_class][table_dest]);
                if (len < 16) {
                        fprintf(stderr, "Short read for num_codes\n");
                        exit(1);
@@ -121,7 +93,53 @@ void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, vo
                        j += tbl->num_codes[i];
                        tbl->maxcode[i] = tbl->huffcode[j - 1];
                }
+
+               // Generate the lookup tables
+               for (unsigned i = 0; i < DEHUF_TABLE_SIZE; ++i) {
+                       tbl->lookup_table_codes[i] = DEHUF_SLOW_PATH;
+                       tbl->lookup_table_length[i] = DEHUF_SLOW_PATH;
+               }
+       
+               unsigned k = 0; 
+               for (unsigned i = 0; i < 16; ++i) {
+                       for (unsigned j = 0; j < tbl->num_codes[i]; ++j, ++k) {
+                               const unsigned code = tbl->huffcode[k];
+                               const unsigned length = tbl->huffsize[k];
+                               if (length > DEHUF_TABLE_BITS) {
+                                       continue;
+                               }
+                               const unsigned prefix_min = code << (DEHUF_TABLE_BITS - length);
+                               const unsigned prefix_max = ((code + 1) << (DEHUF_TABLE_BITS - length));
+
+                               for (unsigned elem = prefix_min; elem < prefix_max; ++elem) {
+                                       assert(tbl->lookup_table_codes[elem] == DEHUF_SLOW_PATH);
+                                       assert(tbl->lookup_table_length[elem] == DEHUF_SLOW_PATH);
+                                       tbl->lookup_table_codes[elem] = tbl->codes[k];
+                                       tbl->lookup_table_length[elem] = length;
+                               }
+                       }
+               }       
        }
 
        free(buf);
 }
+
+unsigned read_huffman_symbol_slow_path(const struct huffman_table* table,
+                                       struct bit_source* source) {
+       possibly_refill(source, 1);
+       unsigned code = read_bits(source, 1);
+       int i = 0;
+
+       while (table->maxcode[i] == -1 || code > (unsigned)table->maxcode[i]) {
+               possibly_refill(source, 1);
+               code = (code << 1) | read_bits(source, 1);
+               ++i;
+
+               if (i > 15) {
+                       fprintf(stderr, "Error in Huffman decoding: Too long code (%x)\n", code);
+                       exit(1);
+               }
+       }
+
+       return table->codes[table->valptr[i] + code - table->mincode[i]];
+}